This invention relates generally to a fluid bed processing system and, more particularly, to a spray gun with a plurality of single nozzles for a fluid bed processing system and a method thereof.
Fluid bed processing systems and methods can be used in a variety of different applications. For example, fluid bed processing systems and methods can be used to dry wet particles for further processing or discharge. Fluid bed processing systems and methods can also be used to coat particles by building identifiable layers evenly over an identified core. Further, fluid bed processing systems and methods can be used to granulate particles into larger aggregates in which the original particles can still be identified in the aggregates.
In fluid bed processing systems and methods, particles to be processed are loaded into a product chamber and are then fluidized into an expansion chamber. If the particles are going to be coated or granulated, a solution is sprayed onto the particles. With the solution, either layers are coated on the particles or the particles begin to aggregate together to form larger particles. The particles dry as they descend down in the expansion chamber and then are blown back up. This up and down process continues until the processing is completed and then the particles are discharged from the product chamber.
In prior fluid bed processing systems and methods, the solution is sprayed out using spray guns which have groups or sets of nozzles, typically groups of three. The nozzles are angled away from each other and away from vertical to achieve a desired spray pattern. Typically, the spray nozzles in each group are positioned between about ten and eighty degrees away from vertical.
One of the problems with these spray guns is that the groups of nozzles have to be spaced apart from each other and from the side wall of the expansion chamber to avoid having their sprays overlap across the expansion chamber. Unfortunately, the spacing needed between groups of nozzles to avoid overlapping sprays reduces the overall spray rate which reduces the overall production throughput of the fluid bed processing system.
Another problem with these spray guns is that the nozzles in each set or group are fed from the same feed stream and thus can not be controlled individually. As a result, the spray rate from one or more of the nozzles may not be set at an optimum level.
Yet another problem with these spray guns is that the mountings for the groups of nozzles are complicated to install and expensive because of the large numbers of parts needed. Because of the additional parts, the mountings are also more likely to need service and/or replacement.
A fluid bed processing system with a spraying apparatus in accordance with one embodiment of the present invention includes an expansion chamber and at least one spraying apparatus which extends into the expansion chamber. The spraying apparatus has a plurality of single nozzles which are spaced along the spraying apparatus. The spraying apparatus also has at least one fluid passage connected to the single nozzles. Each of the single nozzles on the spraying apparatus is positioned to spray fluid in a direction to avoid substantial interaction with spray from the other single nozzles.
A fluid bed processing system with a spraying apparatus in accordance with another embodiment of the present invention also includes an expansion chamber and at least one spraying apparatus which extends into the expansion chamber. The spraying apparatus includes a plurality of fluid passages which extend along at least a portion of the spraying apparatus and a plurality of single nozzles which are spaced along the spray gun and are connected to a different one of the fluid passages.
A method in accordance with another embodiment of the present invention includes loading material to be formed into the particles into a product chamber, fluidizing at least a portion of the material up into an expansion chamber from the product chamber, and spraying a fluid from a plurality of single nozzles in a spray apparatus onto the fluidized powder in directions chosen to avoid substantial interaction between the sprays from each nozzle.
A method for forming enlarged particles from a powder in a fluid bed processing system in accordance with another embodiment of the present invention includes loading material to be formed into larger particles into a product chamber, fluidizing at least a portion of the material up into an expansion chamber from the product chamber, supplying a fluid separately to each of a plurality of single nozzles on a spraying apparatus, and spraying the fluid onto the fluidized material.
With the fluid bed processing system with the spraying apparatus in accordance with the present invention more single nozzles can be deployed in a given cross-sectional area than with prior systems and consequently higher spray rates can be achieved. As a result, the overall production throughput of the fluid bed processing system is increased.
Additionally, with the present invention better control over the direction of spray can be achieved than with prior systems. For example, with the present invention the single nozzles can be positioned closer together and closer to the wall than was possible with prior systems with groups or sets of nozzles.
Further, with single nozzles, the nozzle mountings have been significantly simplified making the single nozzles easier to install and service.